AT&T Wednesday tried to clarify its position on limiting the iOS 6 FaceTime over Cellular feature to its Mobile Share data plan customers. The carrier called concerns that last week’s move might require subscribers change data plans “wrong” and “another knee jerk reaction” about net neutrality.

“The FCC’s net neutrality rules do not regulate the availability to customers of applications that are preloaded on phones. Indeed, the rules do not require that providers make available any preloaded apps,” AT&T said in a blog post. The cell provider said subscribers can download a number of video chat apps that compete with AT&T’s service, a requirement of net neutrality laws…

“To be clear, customers will continue to be able to use FaceTime over Wi-Fi irrespective of the data plan they choose,” the carrier stressed. The company explained it was limiting FaceTime over Cellular “out of an overriding concern for the impact this expansion may have on our network and the overall customer experience.”

Let’s try to cut through the corporate-speak. AT&T is limiting FaceTime over Cellular to Mobile Share customers because it is worried video chatting is so popular, that it could bring down its entire network — and degrade the user experience so much customers complain.

Aside from the explanations, video chatting with FaceTime over Cellular on an iOS 6 iPhone will be more convenient to iPhone owners than downloading a third-party app and making it work. Hint from AT&T: you might want to move to our Mobile Share plan.

Although a throw-away line, the comment about net neutrality rules “do not require that providers make available any preloaded apps” could be the most ominous for Apple. Carriers have always been irked when the Cupertino, Calif. company insists on control over what apps are made available on the iPhone, not wanting carriers to clutter the handset’s desktop with dozens of their own apps. However, carriers have always relented, knowing the iPhone attracts customers willing to pay more for data. But AT&T’s statement may signal a change that they want to be in control of what apps are sold to their subscribers.